1. Field of the Invention
The present invention relates to the field of control systems and methods for use with heating, ventilation, and air conditioning (HVAC) units and particularly to thermostat-based control systems.
2. Prior Art
The present invention relates a microcomputer-controlled thermostat-based system for use in controlling the conditioning of air in multiple zones by way of a single-zone HVAC unit.
A number of methods of controlling the conditions in a plurality of zones from only a single zone HVAC unit are known to the prior art. A description of the difficulties and limitations associated with many of the methods attempted is disclosed in U.S. Pat. No. 4,530,395 (Parker, et al.) and is relevant here. Briefly, the problems center around the means by which a single-zone HVAC unit can be controlled from more than one thermostat. Probably one of the best solutions to this problem that is found in the prior art is disclosed in such patent. The objective there was to provide control of a single zone HVAC unit and its air distribution systems from a common set of thermostats in two or more wherein each thermostat could control both the single zone HVAC unit through a "monitor control" and its own respective zone damper. The system disclosed in such patent provides a "central control monitor" which receives information from the various individual zones and compares this information with various preset data to then properly control the dampers and the HVAC unit. While the system as described did meet the objectives of multiple zone control of a single zone HVAC unit it required the use of a dedicated microprocessor-controlled monitor to receive data from a plurality of zone thermostats. In the present invention, similar control of a single zone HVAC unit for use in multiple zones is accomplished by microcomputer controlled thermostats which can operate in either a slave or master function thus avoiding the need for complex and dedicated central control monitors. It is believed that the system and methods in accord with this invention which allows for control of a single HVAC utilizing master/slave thermostats in lieu of central control units represents a substantial departure from any prior art.